Upper Tangential Arc

This optical effect is not seen very often. It is the point of coincidence of the upper tangential arc and the 22 degree halo giving a 'mock sun' effect.

Normally, mock suns, (aka sundogs or parhelia) are seen 22 degrees either side of the sun but this optical effect is 22 degrees above the sun.

They form in stable air when the majority of ice crystals in high cloud have the same shape and orientation.

This has formed on the backside of storm Christoph.